docs: def _process_pathway_ko(self, limit):
          """
          This adds the kegg orthologous group (gene) to the canonical pathway.
          :param limit:
  
          :return:
          """
          LOG.info("Processing KEGG pathways to kegg ortholog classes")
          if self.test_mode:
              graph = self.testgraph
          else:
              graph = self.graph
          line_counter = 0
  
          raw = '/'.join((self.rawdir, self.files['pathway_ko']['file']))
          with open(raw, 'r', encoding="iso-8859-1") as csvfile:
              filereader = csv.reader(csvfile, delimiter='\t', quotechar='\"')
              for row in filereader:
                  line_counter += 1
                  (ko_id, pathway_id) = row
  
                  if self.test_mode and pathway_id not in self.test_ids['pathway']:
                      continue
  
                  pathway_id = 'KEGG-' + pathway_id
                  ko_id = 'KEGG-' + ko_id
  
                  p = Pathway(graph)
                  p.addGeneToPathway(ko_id, pathway_id)
  
                  if not self.test_mode and limit is not None and line_counter > limit:
                      break
  
          return